(a) Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to an LCD device in which only a data line's own structure is improved to effectively decrease a rubbing defect that occurs in a stepped region of the data line during a rubbing process for alignment of liquid crystal.
(b) Description of the Related Art
In general, a fringe field switching (FFS) mode LCD device has been proposed to improve a low aperture ratio and low transmittance that an in-plane switching (IPS) mode LCD device has.
FIG. 1 is a plan view showing a partial pixel region formed by a manufacturing process in a lower substrate of a conventional FFS mode LCD device, FIG. 2 is a cross-section view of FIG. 1, taken along line A-A′, and FIG. 3 is a conceptual view showing abnormal arrangement of liquid crystal due to a rubbing defect in a stepped region of a data line of FIG. 1.
Referring to FIGS. 1 to 3, the conventional FFS mode LCD device broadly includes a lower substrate 10, an upper substrate (not shown), and a liquid crystal layer (not shown) interposed between the substrates. On the lower substrate 10, pixel regions are respectively defined by gate lines G and data lines 60 formed to intersect each other, and a thin film transistor (TFT) T is arranged as a switching device in an intersecting portion of the gate line G and the data line 60. Further, to adjust the amount of light transmittance by applying voltage to the liquid crystal layer, there are provided a transparent pixel electrode 40 within a pixel region, and a transparent common electrode 80 partially overlapping with and spaced apart from the transparent pixel electrode 40 with an insulating layer 70 therebetween.
Meanwhile, a process of manufacturing the FFS mode LCD device with the above configuration includes a rubbing process for liquid crystal alignment of the liquid crystal layer. As shown in FIGS. 2 and 3, a rubbing defect in a stepped region of the data line 60 causes abnormal alignment of the liquid crystal, different from a desired orientation. In this case, light leakage may occur.
In particular, when an angle between a rubbing direction and a data line is small (i.e., an acute angle), this phenomenon is significantly observed. Generally, in an FFS or a horizontal electric field mode, i.e., IPS mode, the rubbing process may have to be achieved at an acute angle to the data line in accordance with models. At this time, such a rubbing defect remarkably appears in a stepped region opposite to an orientation proceeding direction with respect to the data line.
To solve such a rubbing defect, the shape of pixel has been generally deformed at a certain angle in accordance with a rubbing direction. However, this method causes the whole pixel structure such as the data line 60 to be changed, and is thus disadvantageous in light of the aperture ratio and an efficiency per area.